Andy Pettitte’s legendary work ethic and competitiveness might have had a negative effect on his road back from a fractured left ankle.

An X-ray taken Friday didn’t show the amount of healing Dr. Chris Ahmad, the Yankees’ team physician, wanted to see.

“Obviously it’s healing up, but it hasn’t healed up as much as [Ahmad] thought,’’ Pettitte told The Post before last night’s game against the Red Sox at Yankee Stadium.

Pettitte, 40, pointed to his workout program on the recent West Coast tour that started in Oakland and ended in Seattle as a possible reason for the slower healing.

“In Seattle it swelled up,’’ Pettitte said. “I did a little too much in Seattle. Now I am laying low.’’

Pettitte threw off flat ground with his foot in a boot in Oakland, but wasn’t spotted on the field during the three days in Seattle.

“[Ahmad] didn’t see the healing in weeks two to four that he saw in the first two weeks,’’ Pettitte said. “I have to take it easy.’’

When Pettitte will be able to throw off a mound isn’t known.

“I think it’s healing, but it’s not at the point where he can get off the mound,’’ manager Joe Girardi said.

Pettitte suffered the injury on June 27 when he was struck on the foot by a ball hit by the Indians’ Casey Kotchman.

The original projection was for Pettitte to return by Sept. 1. Now, that might be in jeopardy, although neither Pettitte nor anybody associated with the Yankees said that.

The Yankees’ brass knew about the slower healing situation, and with the trade deadline at 4 p.m. tomorrow, they have to decide if there is anything in a shallow starting pitching pool worth making a deal.

One avenue the Yankees could take is to bolster their bullpen with the knowledge David Phelps, who has been very good in relief, could step into the rotation. The Royals’ Jonathan Broxton is available, as is the Rockies’ Rafael Betancourt, but there doesn’t seem to be a match between Colorado and Yankees.

The Yankees expect Joba Chamberlain back from the disabled list soon, which also should help the bullpen.

Broxton will be a free agent following the season and is making $7 million this year. Betancourt is making $4 million this year, is slated to make $4.25 million next season and has a mutual option for $4.25 million in 2014 with a $250,000 buyout.

As for the starting market, there might be upgrades available but at what price?

The Rays aren’t going to deal James Shields to a division rival. The Marlins’ Josh Johnson is making $13.75 million this year and will take down $13.7 million next year. In addition to the salary, the Marlins would want premier prospects, which is something the Yankees don’t want to move. The Cubs’ Ryan Dempster will be a free agent after this season and their Matt Garza is arbitration-eligible next year after making $9.5 million this year. The Royals’ Bruce Chen is affordable ($4.5 million this year and next), but the money also means the Royals don’t have to move him.

One thing to remember is the Yankees didn’t do anything at the deadline last year and a primary reason was they didn’t want to take on any money for this season.